package cn.cnsuh.剑指offer.q50_第一个只出现一次的字符;

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();

        System.out.println(firstUniqChar(s));
    }

    static char firstUniqChar(String s) {
        if(s == null || s.length() == 0) return ' ';
        Map<Character,Integer> map = new LinkedHashMap<>();
        for(int i = 0 ; i < s.length() ; i++){
            if(!map.containsKey(s.charAt(i))){
                map.put(s.charAt(i),1);
            }else{
                map.put(s.charAt(i),2);
            }
        }


        for(Character c : map.keySet()){
            if(map.get(c) == 1){
                return c;
            }
        }
        return ' ';
    }
}
